27 CFR §25.24

1. (a)Taxpaid beer. Beer of a brewer's own production on which the tax has been paid or determined may not be stored in the brewery, except as provided in § 25.25 or § 25.213. Beer produced by other brewers may be stored at the brewery under the following conditions:
   1. (1)Taxpaid beer will be segregated in such a manner as to preclude mixing with nontaxpaid beer;
   2. (2)If required by part 1 of this chapter, the brewer shall have a wholesalers or importers basic permit under the Federal Alcohol Administration Act, and keep records of the taxpaid beer as a wholesaler or importer under part 31 of this chapter.
   3. (3)Taxpaid beer may be stored in packages;
   4. (4)Taxpaid beer may not be relabeled;
   5. (5)Taxpaid beer may not be shown on required brewery records; and
   6. (6)The appropriate TTB officer may require physical segregation of taxpaid beer, or marking to show the status of taxpaid beer, if necessary to protect the revenue.
2. (b)Untaxpaid beer. Packaged beer on which tax has not been paid or determined may be stored in any suitable location in the brewery.